Any apparatus that processes data records it in its memory or transmits it in a data representation format that specifies the location of the data in the memory or in the stream considered, its structure and its information content. The representation format must be formalized by a descriptor to enable an external user to access the required data items.
Conventionally, the descriptor is provided in the form of a technical specification type of document. The designer of the software program for the utilization of data in an external apparatus can thus identify the useful data (payload) items and develop associated interface functions to locate them, access them and perform a useful reading, i.e. a reading with an understanding of their content. The designer can thus efficiently penetrate the “world” of the apparatus that is the source of the useful data to then translate it into his own “world”, i.e. his own data representation format. Here below in this description, it shall be seen that an apparatus called a data storage apparatus can be the source of data or else the receiver of data. For the simplicity of the description, the examples here below represent the case of a storage apparatus that is a source of data.
There are many possible approaches for solving this problem of conversion of representation formats.
1. Approach Using the Dissemination of Written Specifications
A first “adaptive” type approach leaves the responsibility for the adaptation to the designer of the “external” apparatus that receives and uses the data. All that the designer of the source apparatus does is to give the specification of the data representation to the designer of the user apparatus. Then, from the data representation format thus acquired, the designer of the user apparatus develops an interface driver which enables the processing of data represented in this format. The drawback lies in the fact the user designer must repeat his effort to appropriate the source format as and when this format progresses and develops and must do so for each source apparatus, the data of which he wishes to convert.
2. Approach Using a Standard Format
A second approach, of the type that makes “reference to a standard”, provides that the designer of the source apparatus will develop an interface function to transcribe his data into a standard representation format. The designer of the user apparatus for his part develops a function of an interface towards this standard. Apart from the fact that this standard often causes a loss of information, the two designers have to make the effort to appropriate a third-party, standard format and keep their interface function up to date.
3. Approach Making Available a Software Drive
A third, “driver” type, approach provides that the designer of the source apparatus will develop an interface function to directly process the data that he exports. This interface function is packaged in a program executable by the operating system of the user's apparatus. The drawback is that a specific program needs to be developed for each operating system, and that this program must be broadcast towards potential users.
Document EP 0 936 788 A1 teaches a method of format conversion in which the source format is compared with a first set of target formats which a first converter can process. In the event of failure, i.e. if the first set of available formats does not include that of the final destination user, the data items of the source are converted into an intermediate format, constituted by one of the formats of the first set, which can be recognized by a second downstream converter. The data items having the intermediate format are then, in the same way, compared with a second set of formats of the second converter and the process is repeated iteratively for a determined number of times in an attempt to establish a chaining leading to a final conversion into the destination format. A failure is then declared if the process is unsuccessful. The type of teaching presented in the document EP 0 936 788 A1 is that of the second approach i.e. it is a use of standard known formats. In other words, since the formats are “quantified” and fixed, it is impossible to deviate from a standard. This teaching therefore pertains to a use of one or more cascade-connected converters and in no way to the creation of a converter suited to the requirement presented.